TW201731695A - Surface-protective film and optical component attached with the same - Google Patents

Abstract

The present invention provides a surface protection film applicable for an optical film having an uneven surface, and an optical component using the same. The surface protection film has less contaminants to the adherend which does not change over time. Also, the surface protection film has excellent antistatic performance upon peeling which does not degrade over time. The surface protection film 10 is formed by attaching a release film 5 having a release agent layer 4 on an adhesive layer 2. The release film 5 is formed by laminating the release agent layer 4 on one side of a resin film, wherein the release agent layer 4 includes a release agent having dimethylpolysiloxane as the main component, an antistatic agent not reacting with the release agent, and an adjuvant of the antistatic agent. The component of the antistatic agent is an ionic compound having a melting point of less than 30 DEG C. The component of the adjuvant of the antistatic agent is polyether-modified silicone. The antistatic agent and the adjuvant thereof are transferred to a surface of the adhesive layer 2 from the release agent layer 4 of the release film 5, thereby reducing the electrostatic voltage when the adhesive layer 2 is peeled off from the adherend.

Description

Surface protection film and optical component to which the film is attached

The present invention relates to a surface protective film which is bonded to a surface of an optical element (hereinafter sometimes referred to as an optical film) such as a polarizing plate, a phase difference plate, or a lens film for a display. More specifically, it provides a surface protective film which is less polluted by an adherend, and further, provides a surface protective film having excellent peeling static resistance without time-lapse cracking, and optical using the above surface protective film element.

In the past, optical films such as polarizing plates, phase difference plates, lens films for displays, antireflection films, hard coat films, transparent conductive films for touch panels, and the like, and displays using these films are used. In the case of the product, by adhering the surface protective film to the surface of the optical film, it is possible to prevent dirt, scratches, and the like on the surface in the subsequent step. In the inspection of the optical appearance of the optical film for an optical product, in order to save the workability of peeling off the surface protective film and re-bonding, the work efficiency may be improved, and the surface protective film may be directly bonded to the optical film.

In general, in order to prevent adhesion of scratches, dirt, and the like in the manufacturing process of an optical product, a surface protective film in which an adhesive layer is provided on one surface of a base film is used. The surface protective film is bonded to the optical layer via a micro-adhesive adhesive layer Use on the membrane. The reason why the adhesive layer is set to be slightly viscous is that when the surface protective film after use is peeled off from the surface of the optical film, it can be easily peeled off, and the adhesive is not adhered to remain (that is, the generation of residual glue is prevented). ) on the optical film as a product of the adherend.

In recent years, in the production process of the liquid crystal display panel, although the number of cases occurred is small, the peeling electrostatic voltage generated when the surface protective film attached to the optical film is peeled off is removed, so that it is used for control. Circuit elements such as a driver IC on the display screen of the liquid crystal display panel are damaged, and alignment of liquid crystal molecules is impaired.

Further, in order to reduce the power consumption of the liquid crystal display panel, the driving voltage of the liquid crystal material is lowered, and accordingly, the breakdown voltage of the driving IC is also lowered. Recently, it has been required to strip the electrostatic voltage within the range of +0.7 kV to -0.7 kV.

In addition, in recent years, with the spread of 3D displays (stereoscopic displays), there is a case where an FPR (Film Patterned Retarder) film is bonded to the surface of an optical film such as a polarizing plate. After peeling the surface protection film bonded to the surface of the optical film, such as a polarizing plate, the FPR film is bonded. However, when the surface of the optical film such as a polarizing plate is contaminated with an adhesive, an antistatic agent, or the like used in the surface protective film, there is a problem that it is difficult to adhere the FPR film. Therefore, a surface protective film for the above use is required, which has less contamination of the adherend.

Further, in some liquid crystal panel manufacturers, as a method for evaluating the contamination of an adherend by a surface protective film, a method of temporarily peeling off a surface protective film bonded to an optical film such as a polarizing plate and mixing bubbles therein is employed. In the state, it is bonded again and heat-treated under prescribed conditions, after which the surface protective film is peeled off and the surface of the adherend is observed. In the above evaluation method, even if it is stuck The surface contamination of the object is a trace amount, but if there is a difference in the surface contamination of the adherend between the portion in which the bubble is mixed and the portion in contact with the adhesive of the surface protective film, it is a trace of the bubble (sometimes also Remains in the form of a bubble mark). Therefore, as a method of evaluating the contamination of the surface of the adherend, it is a very strict evaluation method. In recent years, a surface protective film which does not have a problem in terms of contamination of the surface of the adherend even if it is evaluated in accordance with such a strict evaluation method is required.

When the surface protective film is peeled off from the optical film as the adherend, in order to prevent the occurrence of defects due to high peeling of the electrostatic voltage, it has been proposed to suppress the peeling electrostatic voltage to a low level. A surface protective film of an adhesive layer of an antistatic agent.

For example, Patent Document 1 discloses a surface protective film using an adhesive composed of an alkyltrimethylammonium salt, a hydroxyl group-containing acrylic polymer, or a polyisocyanate.

Further, Patent Document 2 discloses an adhesive composition comprising an ionic liquid and an acrylic polymer having an acid value of 1.0 or less, and an adhesive sheet using the above adhesive composition.

Further, Patent Document 3 discloses an adhesive composition comprising an acrylic polymer, a polyether alcohol compound, an alkali metal salt treated with an anion-adsorbing compound, and a surface protective film using the above-described adhesive composition.

Further, Patent Document 4 discloses an adhesive composition comprising an ionic liquid, an alkali metal salt, a polymer having a glass transition temperature of 0 ° C or lower, and a surface protective film using the above adhesive composition.

Further, Patent Document 5 discloses a polymerization comprising a liquid ionic salt. An adhesive composition for a surface protection sheet of an optical element and an adhesive sheet.

[Previous Technical Literature] [Patent Document]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-131957

Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-330464

Patent Document 3: Japanese Laid-Open Patent Publication No. 2005-314476

Patent Document 4: Japanese Laid-Open Patent Publication No. 2006-152235

Patent Document 5: Japanese Laid-Open Patent Publication No. 2008-069261

In the above Patent Documents 1 to 5, an antistatic agent is added to the inside of the adhesive layer. However, the thicker the thickness of the adhesive layer, or the longer it takes to adhere to the adherend, the transfer of the antistatic agent from the adhesive layer to the adherend to which the surface protective film is attached The amount of adherend increases. When the amount of the antistatic agent transferred to the adherend is increased, the appearance quality of the optical film having the adherend is lowered, and the adhesion of the FPR film may be lowered when the FPR film is bonded.

If the thickness of the adhesive layer is reduced in order to reduce the transition of the antistatic agent from the adhesive layer to the adherend as described above, other problems may occur. For example, when an optical film having irregularities on its surface such as a polarizing plate for anti-glare treatment is used, there is a problem in that it is difficult for the adhesive layer to adhere to the unevenness of the surface of the optical film to be mixed with air bubbles or for optical use. The adhesion area between the film and the adhesive layer is reduced to cause a decrease in adhesion, and the surface is used during use. The protective film is floated or peeled off.

Therefore, for the surface protective film used for the film for optics, it is necessary to use an optical film having irregularities on the surface, to have very little contamination of the adherend, and to contaminate the adherend even after a long period of time. The surface protective film is not added, and when the surface protective film is peeled off from the adherend, the peeling electrostatic voltage can be suppressed to a lower surface protective film.

The inventors of the present application have conducted intensive studies in order to solve these problems.

In order to achieve less contamination of the adherend and reduce the time-dependent increase in contamination, it is necessary to reduce the amount of the antistatic agent in the adhesive layer which is presumed to be a cause of contamination of the adherend. However, when the antistatic agent component in the adhesive layer is reduced, the peeling electrostatic voltage when the surface protective film is peeled off from the adherend is increased. Therefore, the present inventors have studied a method of suppressing the peeling electrostatic voltage when the surface protective film is peeled off from the adherend without lowering the absolute amount of the antistatic agent component in the adhesive layer.

As a result, it was found that the adhesive composition containing no antistatic agent was applied and dried on one surface of the base film to form an adhesive composition, and the adhesive composition containing no antistatic agent was applied. After drying and laminating into an adhesive layer, an appropriate amount of an antistatic agent component is applied only to the surface of the adhesive layer, which can suppress the peeling electrostatic voltage when the surface protective film is peeled off from the optical film of the adherend. Thus, the present invention has been completed.

The present invention has been made in view of the above circumstances, and an object of the invention is to provide an optical film having irregularities on its surface, which can be used, has less contamination to adherends, and has low contamination to adherends even after a long period of time. Changing surface protection A film, a surface protective film having excellent anti-peeling electrostatic properties that does not deteriorate with time, and an optical element using the above surface protective film.

In order to solve the above problems, the technical idea of the present invention is that the surface protective film of the present invention is obtained by coating and drying an adhesive composition containing no antistatic agent on one surface of a base film to form an adhesive layer. Thereafter, an appropriate amount of the antistatic agent is applied to the surface of the adhesive layer to suppress the contamination of the adherend, and the peeling static voltage when peeling off from the optical film of the adherend is suppressed. Lower.

In order to solve the above problems, the present invention provides a surface protective film which is formed by forming an adhesive layer on one surface of a base film formed of a resin having transparency, and bonding a release agent layer to the above adhesive layer. The release film is obtained by laminating a release agent layer on one surface of a resin film, wherein the release agent layer contains a release agent containing dimethyl polysiloxane as a main component, and An antistatic agent and an antistatic auxiliary agent which react with the release agent, wherein the antistatic agent component is an ionic compound having a melting point of less than 30 ° C, the antistatic auxiliary agent is a polyether denatured polyfluorene, and the antistatic agent component The antistatic agent is transferred from the release agent layer of the release film to the surface of the adhesive layer to reduce the peeling electrostatic voltage when the adhesive layer is peeled off from the adherend.

Further, the pressure-sensitive adhesive layer is preferably formed by crosslinking reaction of an adhesive composition containing a (meth) acrylate copolymer and a crosslinking agent.

Further, the peeling force when the release film is peeled off from the pressure-sensitive adhesive layer is preferably 0.2 N/50 mm or less.

Further, the present invention provides an optical element obtained by bonding the above surface protective film.

The surface protective film of the present invention has less contamination of the adherend, and the low contamination of the adherend does not change even with time. In addition, the surface protective film of the present invention can be used even if the adherend has an optical film having irregularities on the surface of an AG polarizing plate or the like. Further, according to the present invention, it is possible to provide a surface protective film having excellent anti-peeling electrostatic properties without deterioration with time when the peeling electrostatic voltage generated when peeling off the optical film as an adherend is low. And an optical element using the above surface protective film.

According to the surface protection film of the present invention, the surface of the optical film can be reliably protected, so that productivity can be improved and the yield can be improved.

1‧‧‧Base film

2‧‧‧Adhesive layer

3‧‧‧ resin film

4‧‧‧ Stripper layer

5‧‧‧Release film

7‧‧‧Antistatic agent and antistatic adjuvant

8‧‧‧Adhesive (optical components)

10‧‧‧Surface protection film

11‧‧‧ Stripping the surface protective film of the release film

20‧‧‧Optical components with surface protection film

1] Fig. 1 is a cross-sectional view showing the concept of a surface protective film of the present invention; [Fig. 2] Fig. 2 is a cross-sectional view showing a state in which a release film is peeled off from the surface protection film of the present invention; Fig. 3 is a cross-sectional view showing an embodiment of an optical element of the present invention.

Hereinafter, the present invention will be described in detail through embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing the concept of a surface protective film of the present invention. The surface protection film 10 forms the adhesive layer 2 on the surface of one surface of the transparent base film 1. On the surface of the adhesive layer 2, a surface is formed on the surface of the resin film 3 The release film 5 of the release agent layer 4.

As the base film 1 used in the surface protective film 10 of the present invention, a base film composed of a resin having transparency and flexibility is used. Thereby, the appearance of the optical element can be detected in a state in which the surface protective film is bonded to the optical element as the adherend. As the film composed of the resin having transparency of the base film 1, it is preferable to use polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, poly A polyester film such as butylene terephthalate. In addition to the polyester film, a film composed of another resin may be used as long as it has a desired strength and is optically compatible. The base film 1 may be a non-stretched film or a film which is uniaxially or biaxially stretched. Further, the stretching ratio of the stretched film or the axial orientation angle formed by the crystallization of the stretched film may be controlled to a specific value.

The thickness of the base film 1 used in the surface protective film 10 of the present invention is not particularly limited, and for example, a thickness ranging from 12 to 100 μm is preferable, and a thickness ranging from 20 to 50 μm is preferable. , it is easier to operate and therefore better.

Further, if necessary, an antifouling layer for preventing surface fouling, an antistatic layer, a hard coat layer for preventing scratches, and the like may be provided on the surface of the base film 1 opposite to the side on which the adhesive layer 2 is formed. Further, an easy adhesion treatment such as surface modification by corona discharge or application of an anchoring agent may be performed on the surface of the base film 1.

Further, the adhesive layer 2 used in the surface protective film 10 of the present invention is not particularly limited as long as it is attached to the surface of the adherend, can be easily peeled off after use, and is less likely to contaminate the adhesive of the adherend. In the case of durability and the like after bonding to the optical film, an acrylic adhesive which is crosslinked by a (meth) acrylate copolymer is usually used.

Examples of the (meth) acrylate copolymer include a main monomer such as n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate or isodecyl acrylate, and acrylonitrile, vinyl acetate, and A. Copolymer monomers such as methyl acrylate and ethyl acrylate, functional groups such as acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, and N-methylol methacrylamide A copolymer of a monomer, a polyoxyalkylene group-containing monomer such as methoxypolyethylene glycol methacrylate. (meth) acrylate copolymer, the main monomer and other monomers may be (meth) acrylate, and other monomers other than the main monomer may also contain one or two or more (methyl) Monomers other than acrylate. The monomer other than the main monomer may be selected from, but not limited to, the above comonomer, a functional monomer, a polyoxyalkylene group-containing monomer, and the like.

Examples of the crosslinking agent to crosslink the (meth) acrylate copolymer as the curing agent to be added to the pressure-sensitive adhesive layer 2 include an isocyanate compound, an epoxy compound, a melamine compound, and a metal chelating compound. Further, examples of the tackifier include rosins, scented scorpions, terpenes, terpenes, petroleums, and phenols.

The thickness of the adhesive layer 2 used in the surface protective film 10 of the present invention is not particularly limited, but is preferably in the range of 5 to 40 μm , more preferably in the range of 10 to 30 μm . thickness of. In addition, since the surface protective film is excellent in workability when peeled off from the adherend, the peeling strength (adhesion) of the surface protective film to the surface of the adherend is between 0.03 and 0.3 N/25 mm, and has a slight adhesive force. Adhesive layer 2 is preferred. In addition, since the workability at the time of peeling off the peeling film 5 from the surface protection film 10 is excellent, the peeling force at the time of peeling of the peeling film 5 from the adhesive layer 2 is 0.2 N / 50 mm or less, preferably 0.14 N / 50 mm or less. .

Further, the release film 5 used in the surface protection film 10 of the present invention is formed by laminating a release agent layer 4 on one surface of the resin film 3, and contains a release agent containing dimethyl polysiloxane as a main component. An antistatic agent that does not react with the aforementioned release agent, and an antistatic adjuvant. In the release film used in the surface protective film of the present invention, the antistatic agent component is preferably an ionic compound having a melting point of less than 30 °C. The aforementioned antistatic adjuvant is preferably a polyether-denatured polyfluorene.

Examples of the resin film 3 include a polyester film, a polyamide film, a polyethylene film, a polypropylene film, and a polyimide film. Since it has excellent transparency and a relatively low price, it is preferably polyester. membrane. The resin film may be a non-stretched film or a uniaxial or biaxially stretched film. Further, the stretching ratio of the stretched film and the orientation angle in the axial direction formed by the crystallization of the stretched film can be controlled to a specific value.

The thickness of the resin film 3 is not particularly limited. For example, the thickness is preferably in the range of 12 to 100 μm . If the thickness is in the range of 16 to 50 μm , it is easy to handle, and thus it is more preferable.

Further, an easy adhesion treatment such as surface modification by corona discharge or application of an anchoring agent may be performed on the surface of the resin film 3 as needed.

The release agent containing dimethyl polysiloxane as a main component of the release agent layer 4 may, for example, be a conventional polyoxane-based release such as an addition reaction type, a condensation reaction type, a cationic polymerization type or a radical polymerization type. Agent. Examples of the products of the addition-reactive polyoxo-based release agent which are commercially available include KS-776A, KS-847T, KS-779H, KS-837, KS-778, and KS-830 (Shin-Etsu Chemical Industry ( () manufacturing), SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (Dow Corning) Toray Co., Ltd. manufactures) and the like. For example, SRX-290, SYLOFF-23 (manufactured by Dow Corning Toray Co., Ltd.), and the like are exemplified as the products of the condensation-reaction-type polyoxo-based release agent. For example, TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials Company), and X62-7622 (Shin-Etsu Chemical Industry Co., Ltd.) are listed as products of the cationically polymerized polyfluorene-based release agent. Share) manufacturing) and so on. The products of the radically polymerized polyfluorene-based release agent which are commercially available are X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

As the antistatic agent constituting the release agent layer 4, it is preferred that the dispersant solution containing dimethyl polysiloxane as a main component has good dispersibility and does not hinder dimethylpolysiloxane. The main component of the stripper curing antistatic agent. Further, in order to transfer from the release agent layer 4 to the surface of the adhesive layer 2 and to impart an antistatic effect to the adhesive layer 2, it is preferably an antistatic which does not react with a release agent containing dimethyl polysiloxane as a main component. Agent. An ionic compound having a melting point of less than 30 ° C is very suitable as such an antistatic agent.

The ionic compound having a melting point of less than 30 ° C is an ionic compound having a cation and an anion, and examples of the cation include a cyclic sulfonium ion such as an imidazole ion, a pyridinium ion, an ammonium ion, a cerium ion, and a cerium ion. Further, examples of the anion include C _n H _2n+1 COO ^- , C _n F _2n+1 COO ^- , NO ₃ ^- , C _n F _2n+1 SO ₃ ^- , (C _n F _2n+1 SO ₂ ). ₂ N ^- , (C _n F _2n+1 SO ₂ ) ₃ C ^- , PO ₄ ^3- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , ClO ₄ ^- , BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- and so on.

The amount of the antistatic agent added to the release agent containing dimethylpolysiloxane as a main component differs depending on the type of the antistatic agent, the affinity with the release agent, and the like. The amount of antistatic agent added may be considered to be peeled off from the adherend by the surface protective film. The desired electrostatic discharge voltage, contamination to the adherend, and adhesion characteristics are set.

The antistatic adjuvant constituting the release agent layer 4 is used for the purpose of improving the antistatic property of the surface of the adhesive layer. As such an antistatic auxiliary agent, polyether denatured polyfluorene is preferred. The polyether chain in the polyether denatured polyfluorene is composed of ethylene oxide, propylene oxide, etc., for example, by adjusting the molecular weight of the polyethylene oxide for the side chain, and adjusting the phase with the polyoxynitride stripper Physical properties such as capacitive and antistatic effects.

Further, as a product which is commercially available as a polyether-denatured polyfluorene, for example, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-642 (Shin-Etsu Chemical Industry Co., Ltd.) )), SH8400, SH8700, SF8410 (manufactured by Dow Corning Toray Co., Ltd.), TSF-4440, TSF-4441, TSF-4445, TSF-4446, TSF-4450 (manufactured by Momentive Performance Materials Co., Ltd.) ), BYK-300, BYK-306, BYK-307, BYK-320, BYK-325, BYK-330 (manufactured by BYK).

The amount of addition of the polyether-denatured polyfluorene to the release agent containing dimethylpolysiloxane as a main component varies depending on the type of polyether-denatured polyfluorene and the degree of compatibility with the release agent. It is possible to set the peeling electrostatic voltage, the contamination to the adherend, the adhesive property, and the like which are desired when the surface protective film is peeled off from the adherend.

The method of mixing the release agent containing dimethyl polysiloxane as a main component with the antistatic agent and the antistatic adjuvant is not particularly limited. Any one of the following methods may be used: an antistatic agent and an antistatic adjuvant are added to the release agent containing dimethyl polyoxane as a main component, and after mixing, the release agent is added and mixed to be cured. a method using a catalyst; a method of adding and mixing an antistatic agent, an antistatic agent, and a catalyst for curing a release agent after diluting a release agent containing dimethyl polyoxymethane as a main component in an organic solvent; A method in which a stripping agent containing methylphenoxane as a main component is diluted with an organic solvent in advance, a catalyst is added and mixed, and an antistatic agent and an antistatic adjuvant are added and mixed. Further, if necessary, a material having an auxiliary antistatic effect such as a adhesion improving agent such as a decane coupling agent or a compound containing a polyoxyalkylene group may be added.

The mixing ratio of the release agent containing dimethyl polyoxane as a main component and the antistatic agent and the antistatic adjuvant is not particularly limited, but is a solid relative to a release agent containing dimethyl polysiloxane as a main component. When the composition is 100, the total solid content of the antistatic agent and the antistatic adjuvant is preferably from 5 to 100. The solid content of the release agent containing dimethyl polysiloxane as a main component is 100, and if the ratio of the added amount of the total solid content of the antistatic agent and the antistatic adjuvant is less than 5, the antistatic agent and The amount of transfer of the antistatic auxiliary agent to the surface of the adhesive layer is reduced, and it is difficult to exhibit the function of imparting antistatic to the adhesive. Further, the solid content of the release agent containing dimethyl polysiloxane as a main component is 100, and if the ratio of the added amount of the total solid content of the antistatic agent and the antistatic adjuvant exceeds 100, The release agent containing methyl polysiloxane as a main component is also transferred to the surface of the adhesive layer along with the antistatic agent and the antistatic adjuvant, so that the adhesive property of the adhesive may be lowered.

The method of forming the adhesive layer 2 on the base film 1 of the surface protection film 10 of the present invention and the method of bonding the release film 5 can be carried out by a known method, and are not particularly limited. Specifically, the following method can be mentioned, and any of the methods can be used: (1) coating on one side of the substrate film 1 The resin composition for forming the adhesive layer 2 is dried to form a pressure-sensitive adhesive layer, and then the method of bonding the release film 5; (2) coating the resin for forming the adhesive layer 2 on the surface of the release film 5 The composition is dried and formed to form a pressure-sensitive adhesive layer, followed by a method of bonding the substrate film 1 and the like.

Further, a method of forming the adhesive layer 2 on the surface of the base film 1 may be carried out by a conventional method. Specifically, a conventional coating method such as reverse coating, doctor blade coating, gravure coating, squeezing extrusion coating, metering bar coating, or air knife coating can be used.

Further, similarly, the release agent layer 4 is formed on the resin film 3, and it may be carried out by a known method. Specifically, a conventional coating method such as gravure coating, metering bar coating, or air knife coating can be used.

In the surface protection film 10 of the present invention having the above-described structure, the surface potential when the adhesive layer is peeled off from the optical film as the adherend is preferably from +0.7 kV to -0.7 kV. Further, the surface potential is preferably between +0.5 kV and -0.5 kV, and particularly preferably between +0.1 kV and -0.1 kV. The surface potential can be adjusted by increasing or decreasing the type of the antistatic agent and the antistatic adjuvant contained in the release agent layer, the amount of addition, and the like.

Fig. 2 is a cross-sectional view showing a state in which a release film is peeled off from the surface protection film of the present invention.

By peeling off the release film 5 from the surface protection film 10 shown in FIG. 1, a part of the antistatic agent and the antistatic adjuvant (symbol 7) contained in the release agent layer 4 of the release film 5 are transferred ( Attached to the surface of the adhesive layer 2 of the surface protective film 10. Therefore, in FIG. 2, the antistatic agent and the antistatic adjuvant which are transferred on the surface of the adhesive layer 2 of the surface protective film 11 in the state of peeling off the film are peeled off. It is represented by the spot of symbol 7. By transferring the antistatic agent and the component 7 of the antistatic adjuvant from the release film 5 to the surface of the adhesive layer 2, the adhesive layer 2 is applied from the adherend as compared with the adhesive layer 2 before transfer. The peeling electrostatic voltage at the time of peeling is lowered. Further, the peeling electrostatic voltage when the adhesive layer is peeled off from the adherend can be measured by a known method. For example, after the surface protective film is bonded to an adherend such as a polarizing plate, the surface protective film is peeled off at a peeling speed of 40 m per minute using a high-speed peeling tester (manufactured by TESTER SANGYO CO., LTD.) while using a surface potentiometer. (manufactured by KEYENCE CORPORATION) The surface potential of the surface of the adherend was measured every 10 ms, and the maximum value of the absolute value of the surface potential at this time was taken as the peeling electrostatic voltage (kV).

As the surface protective film of the present invention, when the surface protective film 11 in the state in which the peeling film is peeled off as shown in FIG. 2 is attached to the adherend, the resist is transferred from the release agent layer to the surface of the adhesive layer 2. The electrostatic agent and the antistatic adjuvant are in contact with the surface of the adherend. Therefore, when the surface protective film is peeled off from the adherend again, the peeling electrostatic voltage can be suppressed to be low.

Fig. 3 is a cross-sectional view showing an embodiment of an optical element of the present invention.

The release film 5 is peeled off from the surface protection film 10 of the present invention to expose the surface of the adhesive layer 2, and is bonded to the optical element 8 as an adherend via the adhesive layer 2.

That is, Fig. 3 shows an optical element 20 to which the surface protective film 11 of the present invention is bonded. Examples of the optical element include an optical film such as a polarizing plate, a phase difference plate, a lens film, a polarizing plate which also serves as a phase difference plate, and a polarizing plate which also serves as a lens film. The optical element described above can be used as a constituent element of a liquid crystal display device such as a liquid crystal display panel or an optical system device of various measuring instruments. Also, as optics Examples of the element include an optical film such as an antireflection film, a hard coat film, and a transparent conductive film for a touch panel.

According to the optical element of the present invention, when the surface protective film 11 is peeled off from the optical element (optical film) as the adherend, the peeling electrostatic voltage can be sufficiently suppressed to be low. Therefore, it is possible to improve the production efficiency in the manufacturing process of the liquid crystal display panel and the like, and to maintain the reliability of the production process without worrying about damaging the circuit components such as the driver IC, the TFT element, and the gate line driver circuit.

[Examples]

The invention is further illustrated by the following examples.

(Example 1)

(Production of surface protective film)

5 parts by weight of addition reaction type polyoxyalkylene (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-345), 7.5 parts by weight of tri-n-butylammonium double three of an ionic compound having a melting point of 27.5 ° C Fluroxysulfonimide (manufactured by 3M Company, FC-4400) 10% ethyl acetate solution, 0.3 parts by weight of polyether denatured polyoxyl (manufactured by Dow Corning Toray Co., Ltd., trade name: SH8400), 95 Parts by weight of toluene mixed with ethyl acetate in a 1:1 mixed solvent, 0.05 parts by weight of a platinum catalyst (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-212), stirred and mixed, and prepared for use. A coating of the release agent layer of Example 1 was formed. On the surface of the polyethylene terephthalate film having a thickness of 38 μm , the above-mentioned coating material for forming the release agent layer of Example 1 was coated with a metering rod to have a thickness of 0.2 μm after drying. The film was dried using a hot air circulating oven at 120 ° C for 1 minute to obtain a release film of Example 1. On the other hand, 100 parts by weight of an adhesive polymer solution (solid content: 30% ethyl acetate solution) obtained by dissolving 30 parts by weight of an acrylate copolymer in 70 parts by weight of ethyl acetate, and adding The adhesive composition of Example 1 was prepared by mixing 1.2 parts by weight of an HDI-based curing agent (manufactured by TOSOH CORPORATION, trade name: CORONATE (registered trademark) HX), wherein the acrylate copolymer was obtained by a 96:4 ratio. The weight ratio is obtained by copolymerizing 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate, and has a weight average molecular weight of 470,000. Further, "HDI type" means "hexamethylene diisocyanate".

On the surface of the polyethylene terephthalate film having a thickness of 38 μm , the adhesive composition of Example 1 was applied in such a manner that the thickness after drying was 20 μm , and hot air circulation of 100 ° C was used. The oven was dried for 2 minutes to form an adhesive layer. Thereafter, a release agent layer (polysiloxane treatment surface) of the release film of the above-prepared Example 1 was bonded to the surface of the above-mentioned pressure-sensitive adhesive layer. The obtained adhesive film was kept at 40 ° C for 5 days to cure the adhesive layer, and the surface protective film of Example 1 was obtained.

(Comparative Example 1)

5 parts by weight of an addition reaction type polyoxane (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-345), 95 parts by weight of a mixed solvent of toluene and ethyl acetate of 1:1, 0.05 A part by weight of a platinum catalyst (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-212) was mixed, and the mixture was stirred and mixed to prepare a coating material for forming the release agent layer of Comparative Example 1. On the surface of the polyethylene terephthalate film having a thickness of 38 μm , the above-mentioned coating material for forming the release agent layer of Comparative Example 1 was coated with a metering rod to have a thickness of 0.2 μm after drying. The release film of Comparative Example 1 was obtained by drying in a hot air circulating oven at 120 ° C for 1 minute. On the other hand, with respect to 100 parts by weight of the adhesive polymer solution of Example 1 (solid content of 30% ethyl acetate solution), 3 parts by weight of an ionic compound having a melting point of 27.5 ° C was added and mixed. Butylmethylammonium bistrifluoromethanesulfonimide (manufactured by 3M Company, FC-4400), 10% ethyl acetate solution, 1.2 parts by weight of HDI-based curing agent (manufactured by TOSOH CORPORATION, trade name: CORONATE (registered trademark) HX) The adhesive composition of Comparative Example 1 was prepared.

The adhesive composition of Comparative Example 1 was applied on the surface of a polyethylene terephthalate film having a thickness of 38 μm so as to have a thickness of 20 μm after drying, and then dried using a hot air circulating drying oven at 100 ° C. 2 minutes, an adhesive layer was formed. Thereafter, a release agent layer (polyoxane-treated surface) of the release film of Comparative Example 1 prepared above was bonded to the surface of the pressure-sensitive adhesive layer. The obtained adhesive film was kept at 40 ° C for 5 days to cure the adhesive layer, and the surface protective film of Comparative Example 1 was obtained.

(Comparative Example 2)

A surface protective film of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that tri-n-butylmethylammonium bistrifluoromethanesulfonimide having no ionic compound having a melting point of 27.5 ° C was contained in the adhesive layer.

(Comparative Example 3)

A surface protective film of Comparative Example 3 was obtained in the same manner as in Example 1 except that the polyether-denatured polyfluorene was not contained in the release agent layer.

(Example 2)

In addition to the modification of the adhesive composition of Example 1, an adhesive polymer solution (solid content of 30% ethyl acetate) relative to 30 parts by weight of the acrylate copolymer dissolved in 70 parts by weight of ethyl acetate was used. Solution) 100 weight In the same manner as in Example 1, except that an adhesive composition of 1.2 parts by weight of an HDI-based curing agent (manufactured by TOSOH CORPORATION, trade name: CORONATE (registered trademark) HX) was added and mixed, Example 2 was obtained. a surface protective film obtained by copolymerizing 2-ethylhexyl acrylate, butyl acrylate and 2-hydroxyethyl acrylate in a weight ratio of 60:36:4, and having a weight average molecular weight of 48 Million.

(Example 3)

In addition to the modification of the adhesive composition of Example 1, an adhesive polymer solution (solid content of 30%) was prepared by dissolving 30 parts by weight of the (meth) acrylate copolymer in 70 parts by weight of ethyl acetate. 100 parts by weight of the ethyl acetate solution), and the addition and mixing of 1.2 parts by weight of an HDI-based curing agent (manufactured by TOSOH CORPORATION, trade name: CORONATE (registered trademark) HX), and Example 1 Similarly, the surface protective film of Example 3 was obtained. Wherein the (meth) acrylate copolymer comprises 2-ethylhexyl acrylate, methoxy polyethylene glycol (400) methacrylate, and acrylic acid 2 by weight: 86:10:4. - Hydroxyethyl ester copolymerized, having a weight average molecular weight of 380,000.

The methods and results of the evaluation test are shown below.

<Method for Measuring Peel Force of Release Film>

The sample of the surface protective film was cut into a width of 50 mm and a length of 150 mm. In a test environment of 23 ° C × 50% RH, the strength at the time of peeling off the release film was measured at a peeling speed of 300 mm/min and a direction of 180° using a tensile tester, and this was used as a peeling force of the release film (N/ 50mm).

<Method for Measuring Adhesion of Surface Protective Film>

The anti-glare low-reflection polarizing plate (AG-LR polarizing plate) was attached to the surface of the glass plate by using a double-sided adhesive tape using a bonding machine. Then, after the surface protective film cut to a width of 25 mm was attached to the surface of the polarizing plate, it was stored in a test environment of 23 ° C × 50% RH for one day. Thereafter, the strength at the time of peeling off the surface protective film was measured at a peeling speed of 300 mm/min and a direction of 180° using a tensile tester, and this was used as an adhesive force (N/25 mm).

<Method for Measuring Peeling Electrostatic Voltage of Surface Protective Film>

The anti-glare low-reflection polarizing plate (AG-LR polarizing plate) was attached to the surface of the glass plate by using a double-sided adhesive tape using a bonding machine. Thereafter, a surface protective film cut to a width of 25 mm was attached to the surface of the polarizing plate, and then stored in a test environment of 23 ° C × 50% RH for one day. Then, the surface protective film was peeled off at a peeling speed of 40 m per minute using a high-speed peeling tester (manufactured by TESTER SANGYO CO, LTD.), and the surface potential of the surface of the polarizer was measured every 10 ms using a surface potentiometer (manufactured by KEYENCE CORPORATION), and The absolute value of the absolute value of the surface potential at this time was taken as the peeling electrostatic voltage (kV).

<Method for Confirming Surface Contamination of Surface Protective Film>

The anti-glare low-reflection polarizing plate (AG-LR polarizing plate) was attached to the surface of the glass plate by using a double-sided adhesive tape using a bonding machine. Then, a surface protective film cut to a width of 25 mm was attached to the surface of the polarizing plate, and then stored in a test environment of 23 ° C × 50% RH for 3 days and 30 days. Thereafter, the surface protective film was peeled off, and the presence of contamination on the surface of the polarizing plate was visually observed. As a criterion for determining the degree of surface contamination, the case where no contamination was transferred on the polarizing plate was evaluated as (○), and the case where contamination transfer was observed on the polarizing plate was evaluated as (×).

The measurement results of the obtained surface protective films of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Tables 1 and 2. "2EHA" is 2-ethylhexyl acrylate, "HEA" is 2-hydroxyethyl acrylate, "BA" is butyl acrylate, and "#400G" is methoxypolyethylene glycol (400) methacrylate "FC4400" is tri-n-butylammonium bistrifluoromethanesulfonimide. In Tables 1 and 2, the composition of the adhesive layer is expressed by weight parts in such a manner that the total amount of the adhesive polymer (solid content) is about 100 parts by weight. Therefore, in the adhesive layer of Comparative Example 1, the weight ratio of the adhesive polymer (solid content) to FC4400 was 30 parts by weight: 0.3 parts by weight = 100 parts by weight: 1.0 part by weight.

〔Table 2〕

According to the measurement results shown in Tables 1 and 2, the following conclusions can be obtained.

The surface protective films of Examples 1 to 3 of the present invention have a moderate adhesive force, do not contaminate the surface of the adherend, and have a low peeling electrostatic voltage when the surface protective film is peeled off from the adherend.

On the other hand, the surface protective film of Comparative Example 1 containing an antistatic agent in the adhesive layer has a low peeling electrostatic voltage when the surface protective film is peeled off from the adherend, but is good for the adherend after peeling. Increased pollution.

Further, in the surface protective film of Comparative Example 2, in which both the adhesive layer of the surface protective film and the release agent layer of the release film did not contain an antistatic agent, the contamination to the adherend was good, but the surface protection was performed. The peeling electrostatic voltage when the film is peeled off from the adherend is increased.

That is, a comparative example containing an antistatic agent in the adhesive layer of the surface protective film In the surface protective film of Comparative Example 2 in which the surface protective film of 1 and the adhesive layer of the surface protective film and the release agent layer of the release film do not contain an antistatic agent, it is difficult to achieve both reduction of the peeling electrostatic voltage and adhesion to the adherend. Pollution.

On the other hand, after the anti-static agent and the antistatic auxiliary agent are contained in the release agent layer of the release film, the antistatic agent and the antistatic adjuvant which are only transferred with the release agent layer on the surface of the adhesive layer are used. The surface protective film of ~3 has a remarkable effect of reducing the peeling static voltage by adding a small amount of the antistatic adjuvant. Therefore, it is not contaminated by the adherend, and the anti-peeling electrostatic property is also good.

Further, in the surface protective film of Comparative Example 3 in which only the antistatic agent was contained in the release agent layer and the antistatic auxiliary agent was not contained, there was no contamination of the adherend, and the anti-peeling electrostatic performance was also good. However, when the surface protective film of Examples 1 to 3 containing the antistatic agent and the antistatic auxiliary agent in the release agent layer is used, the peeling electrostatic voltage is increased.

[Industrial Applicability]

The surface protective film of the present invention can be used for bonding the optical element to protect the surface in the production steps of an optical film such as a polarizing plate, a retardation film, and a lens film, and other various optical elements. Further, the amount of static electricity generated when the surface protective film of the present invention is peeled off from the adherend is low, and the change in the anti-peeling electrostatic property with time and the contamination of the adherend are small, and the yield of the production step can be improved. The industrial use value is large.

1‧‧‧Base film

2‧‧‧Adhesive layer

3‧‧‧ resin film

4‧‧‧ Stripper layer

5‧‧‧Release film

7‧‧‧Antistatic agent and antistatic adjuvant

10‧‧‧Surface protection film

Claims (4)

A surface protective film which is formed by forming an adhesive layer on one surface of a base film composed of a resin having transparency, and attaching a release film having a release agent layer to the adhesive layer. The surface protective film is characterized in that the release film is formed by laminating the release agent layer on one side of a resin film, wherein the release agent layer contains dimethyl polysiloxane as a main component. a stripping agent, an antistatic agent not reacting with the stripping agent, and an antistatic agent component, wherein the antistatic agent component is an ionic compound having a melting point of less than 30 ° C, and the antistatic auxiliary agent is a polyether denatured polyoxyl The antistatic agent component and the antistatic adjuvant are transferred from the release agent layer of the release film to the surface of the adhesive layer to reduce the peeling electrostatic voltage when the adhesive layer is peeled off from an adherend. The surface protective film according to claim 1, wherein the adhesive layer is formed by crosslinking an adhesive composition containing a (meth) acrylate copolymer and a crosslinking agent. The surface protective film according to claim 1 or 2, wherein a peeling force when the release film is peeled off from the adhesive layer is 0.2 N/50 mm or less. An optical element obtained by laminating a surface protective film according to any one of claims 1 to 3.